Do you mean a shared brand that several publishers can use? I don't know of any. You may try asking ENPub if you can license their PnM brand or collect enough publishers to create your own, new brand.
Yes, I'm looking for a shared brand that people new to e-publishing can use. I was attracted to Pick 'n' Mix mainly because the layout was already taken care of. As someone new to e-publishing PnM offered me a way to gently ease myself into the publishing world, get some feedback and re-evaluate things based on that feedback.